Modern-Type Eolian Regime and Global Cooling-Modulated Dust Provenance in the Late Paleogene of Central-East Asia

Katja Bohm, Joonas Wasiljeff, Thomas Stevens, Johanna Salminen, Hui Tang, Yann Lahaye, Matti Kurhila, Zaoqun Zhang, Ove Westermoen Haugvaldstad, Anu Kaakinen

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Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi-technique provenance analysis of a rare Paleogene (35-27 Ma) eolian dust sequence from Ulantatal, similar to 400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene-Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)-like situation, and that the warm Eocene favored a long-term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene-Oligocene transition (EOT), long-term positive phase of AO-like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern-type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern-type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene.
TidskriftGeochemistry, geophysics, geosystems G³.
Antal sidor23
StatusPublicerad - feb. 2024
MoE-publikationstypA1 Tidskriftsartikel-refererad


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